Iron oxide zeta potential

Carlson, J. J., Kawatra, S. K. (2013). Factors affecting zeta potential of iron oxides. Mineral Processing and Extractive Metallurgy Review, 34(5), 269-303. doi 10.1080/08827508.2011.604697... 

Tipping (1981) showed that the adsorption of terrestrial humic substances could reverse the positive electrophoretic mobility of iron oxides. Thus, both terrestrial and marine organics are strong adsorbates, able to reverse zeta potential. 

All povidone types can be used as hydrophilic polymers to physically stabilize suspensions [39,119]. Their most important and primary function in all suspensions is as protective colloids, which hydrophilize the individual solid particles and sterically separate them. This increases the volume of any sediment and makes it easier to redisperse by shaking. Povidone also prevents the dissolved portion of the active substance from crystallizing out by forming soluble complexes with it [389] (see also Sections 2.2.7 and 2.4.5). The Zeta potential of many substances, e. g. iron oxide pigments, can also be reduced with povidone [421]. 

Kunzelmann, U., Jacobasch, H.J., and Reinhard. G., Investigations of the influence of vapour phase inhibitors on the surface charge of iron oxide particles by zeta-potential measurements, Werkstoffe Korrosion. 40, 723, 1989. 

Mullet, M. et al.. Surface electrochemical properties of mixed oxide ceramic membranes Zeta-potential and surface charge density, J. Membr. Sci.. 123, 255, 1997. Kanungo, S.B. and Mahapatra, D.M., Interfacial properties of two hydrous iron oxides in KNO3 solution. Colloids Surf., 42, 173,1989. 

Crawford, R.J., Harding, LH., and Mainwaring, D.E., The zeta potential of iron and chromium hydrous oxides during adsorption and coprecipitation of aqueous heavy metals, J. Colloid Interf. Sci., 181, 561, 1996. 

Hunter, R. J., Zeta Potential in Colloid Science, Academic Press, London, 1931. Hackley, V. A., and Anderson, M. A., Effects of short-range forces on the long-range structure of hydrous iron oxide aggregates, Langmuir, 5, 191-198 (1989). Hansmann, D. D., and Anderson, M. A., Using electrophoresis in modeling sul-... 

When a DC potential is applied to a medium containing water and ions, such as soil, acid is generated at the anode and base at the cathode due to the electrolysis of water. The highly acidic environment near the anode could be detrimental to the electroosmosis process if the zeta potential in the soil falls too low or reverses. Two clever approaches are utilized in the Lasagna process to both minimize the acid effect on soil and keep the anode pH between 5 and 7. First, steel plates are used as the anode material to promote iron oxidation as the main anodic reaction instead of water oxidation, which forms acid (H+). Second, the basic pore water accumulated at the cathode (pH > 12) is recycled by gravity back to the anode as makeup water, which is required for continuing the operation of electroosmosis and at the... 

It would be hard to overestimate the significance of this new procedure, however. There is a great deal of difficulty attached to the problem of finding a suitable standard material, especially for the zeta potential. Different manufacturers and standardizing bodies have produced different materials the National Institute of Standards and Technology in Washington, for example, provides a standard iron oxide which, if made up to a defined recipe, is reported to give reproducible results for Q. Here, we have a procedure... 

Crawford et al. (1996) measured the zeta potential of amorphous hydrous iron (III) oxide (HFO) and amorphous hydrous chromium (III) oxide (HCO) as a function of pH during adsorption and coprecipitation of Cr +, Zn +, and Ni. For sand materials, the zeta potential is negative and it increases as the pH increases (Elimelech et al., 2000). 

Fig. 1. The zeta potential of micrometric iron oxide (Fe304) dispersions containing ionic liquids.

The interaction of hydrocarbon and fluorocarbon surfactants on the surface of dispersed particles has been studied through a flocculation and redispersion process [65-67]. Dispersions of positively charged particles can be flocculated with an anionic surfactant. An excess of the anionic surfactant forms a bilayer on the particle surface and causes redispersion of the flocculated sol. This flocculation reversal was used to study the interaction between mixed surfactants on a solid surface. A dispersion of iron(ITI) oxide hydrate particles was flocculated with an anionic hydrocarbon or fluorocarbon surfactant at pH 3.5, where the sols had a positive zeta potential. Subsequently, a second fluorocarbon or hydrocarbon surfactant was added to the flocculated sol. The extent of redispersion depended on the interaction between the two surfactants on the solid particle surface. 

Changes in zeta potential and turbidity of iron(III) oxide hydrate sols flocculated by sodium dodecyl sulfate (SDS) are shown in Fig. 5.9. When SDS was... 

Figure 5.10 shows changes in zeta potential and turbidity of iron(III) oxide hydrate sols flocculated with NFIOO. The optimum flocculation concentration was about 3 X 10 mM NFIOO. The sols were redispersed by NF7 or NP7.5, a hydrocarbon-type nonionic surfactant (polyoxyethylene nonylphenyl ether with a polyoxyethylene chain of average 7.5 EO). The turbidity increased sharply. The zeta potential changed only a little, as expected for a nonionic surfactant. Sols flocculated by NFIOO were not redispersed by SDS. The inability of SDS, an anionic hydrocarbon surfactant, to redisperse the sols was attributed... 

Changes in zeta potential and turbidity of iron(III) oxide hydrate sols flocculated with lithium perfluorooctanesulfonate (LiFOS) are shown in Fig. 5.11. The nonionic surfactants NF7 and NP7.5 redispersed the sols. However, the anionic hydrocarbon surfactant LiDS (lithium dodecyl sulfate) had no significant effect. Accordingly, sols flocculated by LiDS were redispersed by a nonionic surfactant, NF7, but not by the anionic surfactant LiFOS (Fig. 5.12). 

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